Any Electro-Magnetic Field is actually made up from two separate component fields. The Electric Field and the Magnetic Field. EMF - the term we all commonly use to describe these fields is actually wrong. In Physics an EMF refers to an Electro-Motive Force and is a term describing the electrical potential between two points of an electrical circuit. However in recent years it has become a universally accepted abbreviation for Electro-Magnetic Fields. An EMF is the Invisible lines of force produced by voltage and current that surround any electrical device or electrical power line. They can also exist separately from each other, Electric fields are produced by most living and many non-living organisms and objects. Magnetic fields are only produced by materials that are naturally magnetic - Ferrous metals and some minerals for example or whenever an electrical current flows through a conducting body, such emissions always have an associated electric field too.

There are two types of radiating electro-magnetic emissions, The Non-Ionising and the Ionising. The Electromagnetic spectrum extends from the ultra short wave lengths that comprise ionising radiation and x-rays down into the non-ionising portion of the spectrum such as the visible light, radio waves and finally into the Earth's own Geo magnetic field, often described as being DC, i.e. without any frequency. Sound waves are not part of this spectrum as they are produced by the movement of acoustic waves through a physical medium such as air or water.

Researchers have been extending their search into many areas of the EM spectrum in the desire to try and obtain answers to the puzzles of the paranormal. Most recent research has concentrated upon the lower regions of the EM spectrum with research into magnetic and what are termed electro-magnetic fields. These studies have centred on lab based research by Parapsychologists and Physicists in several countries.

Magnetic fields from the Earth have been suggested as possible explanations for many unusual reports including UFO related events, Poltergeists and Hauntings. The current research seems to show that some people's brains may be more susceptible than others to these emissions, creating electrical activity within the brain that may then be interpreted as being of a paranormal origin. Of course, we have developed to use and trust our 5 senses and the brain can only interpret this interference in a sensory manner - therefore, they may see, hear, taste, touch or smell something and believe it to be anomalous. EM radiation does seem to affect PSI abilities too, for example; it has been noticed that success in PSI tests and reports of spontaneous PSI experiences have appeared to decrease at times when there are high fluctuations in the local geomagnetic field.

The geomagnetic field strength is normally between 20,000 and 50,000 nano-Tesla (nT) - 200~500 milli Gauss (mG) depending upon where in the world it is measured. Other factors including local geology and the presence of both Ferrous and non-Ferrous metals for example in the construction of a building metal, all affect the precise level as does changes to the amount of solar radiation that is received on Earth.

Electro-magnetic fields at 50Hz and 60 Hz are produced by the mains electric supply. These frequencies are very close to those naturally produced by the human body (less than 100Hz) and by the brain itself, which operates at frequencies below 50Hz. It is perhaps therefore not too surprising to learn that exposure to some types of EMF can have a measurable effect on human physiology and behaviour. Some research has suggested that exposure may even by harmful and is the main reason why there are so many EMF detectors available in this increasingly health conscious world.

So far, Lab based studies have included placing subjects into fluctuating random magnetic fields generated by two large coils that the subject sits in between or have had low amplitude EMFs directed into the brain. Much of the pioneering work has been carried out in Canada by Professor M.A. Persinger. Many test subjects reported experiences that were suggestive of paranormal experiences, such as feelings of being watched and touched, a presence in the room with them and the hearing of voices. At a range of specific frequencies the subjects even reported experiences that were remarkably similar to the Near Death Experience (NDE).

Following on from this research it was postulated that a person in the everyday environment might also have these same experiences if they are subjected to similar EM fields. Many similar EM fields have been measured in the real world - power cables, computers, TVs and mobile phones have all been found to have a similar EMF to those used in the lab experiments. If these people then went on to have an experience that was 'induced' by the EMF without being aware of the EMF being the cause then they might then go on to say that they had experienced the 'paranormal'.

So far all of this research has been confined to the lab with some limited studies carried out in the field, where it seems that the environmental EMFs are indeed linked to anomalous personal experiences. In one experiment in a haunted part of Edinburgh test volunteers reported a higher number of feelings of being watched or uncomfortable in particular areas where the EMF was higher than in areas where no 'paranormal' activity had been reported.

Many ghosthunters carry an EMF detector. In fact the EMF detector is the current number 1 'must have' tool for any self respecting ghosthunter and to an extent Ufologists as well. Most of the devices that are marketed and affordable by the average paranormal investigator are designed purely to measure the amount of EMF that is given off by domestic appliances at 50Hz . Even worse, are the ones made for the American market that are calibrated at 60Hz. These devices simply measure too high a frequency to be of any use. Laboratory experiments have indicated that the critical frequencies that affect the mind are much lower, in the 0.5Hz - 30Hz range.

Brain activity is seen typically in ranges referred to by Greek letters: Delta (0.5-4Hz), Theta (5-7Hz), Alpha (8-12Hz), Beta (18-30Hz) and Gamma (30-50Hz). It is the lower ranges - Delta - Beta that typically cause the subject to experience events that they may describe as being paranormal. Equipment to measure EMF in these ranges is rare and almost without exception very expensive. Most paranormal Investigators simply do not possess such tools but some recent field work has suggested that the affects of amplitude and frequency changes within the main electrical supply may also be linked to some anomalous reports.

There is a disturbing trend seen in recent years and one that seems to be spreading rapidly! That is shown by groups who possess Electro-Magnetic field measuring instruments without any knowledge whatsoever what they are looking for or even why. Many also believe that ghosts emit or give off EMF radiation and that when their EMF detector 'goes off' then it has detected the presence of a ghost. As far as is known ghosts are not known for their ability to radiate Electro-magnetic energy and so such an idea is counter-productive and unlikely to further our knowledge. Most of this poor information comes from the Internet, and may be further compounded by a number of TV shows that claim to be investigating the paranormal and appear to be using these EMF detectors as 'Ghost Detectors'. Many paranormal groups have recently sprung up, their enthusiasm fired by such shows, they invariably rush out to buy their own 'EMF' meter and without a backward glance at the research material suddenly have the means to detect ghosts and ghostly activity. To make matters worse still, these 'investigators' then go on to encounter perfectly normal EMF levels that trigger their detector and after a quick sweep over the mains wiring to pronounce it not the cause they happily declare the location haunted.

In truth, EMF's are to be found within most environments and locations and with a huge variation in their amplitude too. It is therefore wrong to simply assume that any EMF that is detected is of an anomalous or paranormal origin without extensive testing. Even then, the tools that are available may simply be the wrong item of equipment and may not be capable of detecting the causal emissions. As an example, consider a single-axis EMF meter, which is the most commonly found type of meter in the ghost hunters kit box. This is only capable of measuring an EMF radiation in one direction. EMF's are present in the form of a circular or spherical field surrounding the source. Moreover the two components of the EMF - the Electric Field and the Magnetic Field are at right-angles to one another. Therefore, if the alignment of the EMF meter sensor is not directly in line with the emission direction the meter will give a misleading reading or may not even be able to 'see' the field at all.

It must also be remembered that EMF meters are also specifically designed to measure within a specific range of frequencies (commonly 50 or 60Hz) and that outside that range they cannot produce reliable measurements. They also cannot indicate what the frequency of the EMF they are measuring is and so the information they supply can only ever be treated as a guide to the actual emission levels, rather than as a definitive measurement and even then only within a defined range of frequencies. Despite the claims, to the best of our current knowledge no such Ghost Detection device exists.

Looking at those EMF meters that are available to the amateur paranormal investigator one sees a very wide range of usefulness. Basic meters costing just a few tens of dollars - like the CellSensor® and the Dr. Gauss® may just be sufficient for an experienced investigator to estimate the levels of EM radiation from sources such as man-made electrical appliances and cables. In actual fact they are not strictly EMF meters at all - they only measure and display the magnetic field component, hence they display the results in units of magnetic measurement i.e. milli Gauss (mG). Moving up to the single-axis digital or higher specification meters including the Aaronia MultiDetektor II Profi and the standard AlphaLabs TriField® meter, permits more accurate measurements to be obtainable in 1 or more axes. These meters also provide the opportunity to make separate measurement of the two-parts of the EMF - the Electric field and the Magnetic field, units of measurement are mG for the magnetic field and Volts/ metre (V/m) for the electric field. Towards the top of the amateur price-range are the digital 3-axis meters that have the ability to measure both types of field, simultaneously and separately.

Beyond this are some expensive items of equipment that are capable of directly measuring the Earth's DC local magnetic field and also emissions at a broad range of AC frequencies above that. Traditionally used in laboratory research, recently some investigators have shared resources to acquire these pieces of equipment so they are now being used to explore haunted locations for the first time.

Regardless of the type of EMF meter you may have, provided it is used correctly and wisely they are all capable of providing the paranormal investigator with useful and potentially helpful information. However, even the most expensive and accurate meter if used incorrectly or without genuine knowledge of what the presented information may mean will only result in wasted effort and meaningless data being collected.

There is a further type of EMF meter that is extensively used by Paranormal Investigators that needs to be considered here too. The Natural EM TriField® meter made by AlphaLab is designed to measure only changes within an Electromagnetic field - i.e. it only gives a reading when it detects that the level of the either the magnetic field or the electric field is changing, the meter reads Zero in a stable and unchanging field. It is also a true 3-axis meter unlike the Standard TriField® models.

Changing fields are important within paranormal research as the lab studies carried out so far by Professor M.A. Persinger have indicated that the brain may also be affected by fluctuations within the overall field strength rather than just simply changes within its overall amplitude. The Natural EM TriField® is currently the only hand-held stand-alone device that allows paranormal investigators to look at changes within the field strength. Other meters, such as the Model 1394 Tri-axial digital meter that can be linked to a PC for either real-time or data-logging of the EM field strength can be used for greater degrees of accuracy and at a slightly higher cost.